Guys: why would you keep doing it if...?

Couple of points:

1- Leaving out the why the guys are asking for pictures, the question you might want to ask yourself is why are you uncomfortable sending pictures? Are you uncomfortable with your body? or some small portion of your how you look? or are you afraid of the emotions that come from doing this?

If you just not photogenic, then say that up front. If it's something else that's bothering you, you might want to figure it out and address it in some way.

2- Several reasons that guys are asking for pics: One, they are visual, as are girls. Two, they don't really want any kind of a commitment or to do any kind of work, so a picture gives them a small sense of accomplishment, like they did actually something to be "social" with girls, so now they don't have to actually go out there and talk to somebody in person. Three, they might be pervs and not actual real guys, watch out for those.

If you feel like it's something you don't want to do, switch to a different form of interacting, go to the mall instead of talking online or something along those lines.